[mirror_zfs.git] / module / zfs / txg.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <sys/zfs_context.h>
#include <sys/txg_impl.h>
#include <sys/dmu_impl.h>
#include <sys/dsl_pool.h>
#include <sys/callb.h>

/*
 * Pool-wide transaction groups.
 */

static void txg_sync_thread(dsl_pool_t *dp);
static void txg_quiesce_thread(dsl_pool_t *dp);

int zfs_txg_timeout = 30;	/* max seconds worth of delta per txg */

/*
 * Prepare the txg subsystem.
 */
void
txg_init(dsl_pool_t *dp, uint64_t txg)
{
	tx_state_t *tx = &dp->dp_tx;
	int c;
	bzero(tx, sizeof (tx_state_t));

	tx->tx_cpu = kmem_zalloc(max_ncpus * sizeof (tx_cpu_t), KM_SLEEP);

	for (c = 0; c < max_ncpus; c++) {
		int i;

		mutex_init(&tx->tx_cpu[c].tc_lock, NULL, MUTEX_DEFAULT, NULL);
		for (i = 0; i < TXG_SIZE; i++) {
			cv_init(&tx->tx_cpu[c].tc_cv[i], NULL, CV_DEFAULT,
			    NULL);
		}
	}

	rw_init(&tx->tx_suspend, NULL, RW_DEFAULT, NULL);
	mutex_init(&tx->tx_sync_lock, NULL, MUTEX_DEFAULT, NULL);

	cv_init(&tx->tx_sync_more_cv, NULL, CV_DEFAULT, NULL);
	cv_init(&tx->tx_sync_done_cv, NULL, CV_DEFAULT, NULL);
	cv_init(&tx->tx_quiesce_more_cv, NULL, CV_DEFAULT, NULL);
	cv_init(&tx->tx_quiesce_done_cv, NULL, CV_DEFAULT, NULL);
	cv_init(&tx->tx_exit_cv, NULL, CV_DEFAULT, NULL);

	tx->tx_open_txg = txg;
}

/*
 * Close down the txg subsystem.
 */
void
txg_fini(dsl_pool_t *dp)
{
	tx_state_t *tx = &dp->dp_tx;
	int c;

	ASSERT(tx->tx_threads == 0);

	rw_destroy(&tx->tx_suspend);
	mutex_destroy(&tx->tx_sync_lock);

	cv_destroy(&tx->tx_sync_more_cv);
	cv_destroy(&tx->tx_sync_done_cv);
	cv_destroy(&tx->tx_quiesce_more_cv);
	cv_destroy(&tx->tx_quiesce_done_cv);
	cv_destroy(&tx->tx_exit_cv);

	for (c = 0; c < max_ncpus; c++) {
		int i;

		mutex_destroy(&tx->tx_cpu[c].tc_lock);
		for (i = 0; i < TXG_SIZE; i++)
			cv_destroy(&tx->tx_cpu[c].tc_cv[i]);
	}

	kmem_free(tx->tx_cpu, max_ncpus * sizeof (tx_cpu_t));

	bzero(tx, sizeof (tx_state_t));
}

/*
 * Start syncing transaction groups.
 */
void
txg_sync_start(dsl_pool_t *dp)
{
	tx_state_t *tx = &dp->dp_tx;

	mutex_enter(&tx->tx_sync_lock);

	dprintf("pool %p\n", dp);

	ASSERT(tx->tx_threads == 0);

	tx->tx_threads = 2;

	tx->tx_quiesce_thread = thread_create(NULL, 0, txg_quiesce_thread,
	    dp, 0, &p0, TS_RUN, minclsyspri);

	/*
	 * The sync thread can need a larger-than-default stack size on
	 * 32-bit x86.  This is due in part to nested pools and
	 * scrub_visitbp() recursion.
	 */
	tx->tx_sync_thread = thread_create(NULL, 12<<10, txg_sync_thread,
	    dp, 0, &p0, TS_RUN, minclsyspri);

	mutex_exit(&tx->tx_sync_lock);
}

static void
txg_thread_enter(tx_state_t *tx, callb_cpr_t *cpr)
{
	CALLB_CPR_INIT(cpr, &tx->tx_sync_lock, callb_generic_cpr, FTAG);
	mutex_enter(&tx->tx_sync_lock);
}

static void
txg_thread_exit(tx_state_t *tx, callb_cpr_t *cpr, kthread_t **tpp)
{
	ASSERT(*tpp != NULL);
	*tpp = NULL;
	tx->tx_threads--;
	cv_broadcast(&tx->tx_exit_cv);
	CALLB_CPR_EXIT(cpr);		/* drops &tx->tx_sync_lock */
	thread_exit();
}

static void
txg_thread_wait(tx_state_t *tx, callb_cpr_t *cpr, kcondvar_t *cv, uint64_t time)
{
	CALLB_CPR_SAFE_BEGIN(cpr);

	if (time)
		(void) cv_timedwait(cv, &tx->tx_sync_lock, lbolt + time);
	else
		cv_wait(cv, &tx->tx_sync_lock);

	CALLB_CPR_SAFE_END(cpr, &tx->tx_sync_lock);
}

/*
 * Stop syncing transaction groups.
 */
void
txg_sync_stop(dsl_pool_t *dp)
{
	tx_state_t *tx = &dp->dp_tx;

	dprintf("pool %p\n", dp);
	/*
	 * Finish off any work in progress.
	 */
	ASSERT(tx->tx_threads == 2);
	txg_wait_synced(dp, 0);

	/*
	 * Wake all sync threads and wait for them to die.
	 */
	mutex_enter(&tx->tx_sync_lock);

	ASSERT(tx->tx_threads == 2);

	tx->tx_exiting = 1;

	cv_broadcast(&tx->tx_quiesce_more_cv);
	cv_broadcast(&tx->tx_quiesce_done_cv);
	cv_broadcast(&tx->tx_sync_more_cv);

	while (tx->tx_threads != 0)
		cv_wait(&tx->tx_exit_cv, &tx->tx_sync_lock);

	tx->tx_exiting = 0;

	mutex_exit(&tx->tx_sync_lock);
}

uint64_t
txg_hold_open(dsl_pool_t *dp, txg_handle_t *th)
{
	tx_state_t *tx = &dp->dp_tx;
	tx_cpu_t *tc = &tx->tx_cpu[CPU_SEQID];
	uint64_t txg;

	mutex_enter(&tc->tc_lock);

	txg = tx->tx_open_txg;
	tc->tc_count[txg & TXG_MASK]++;

	th->th_cpu = tc;
	th->th_txg = txg;

	return (txg);
}

void
txg_rele_to_quiesce(txg_handle_t *th)
{
	tx_cpu_t *tc = th->th_cpu;

	mutex_exit(&tc->tc_lock);
}

void
txg_rele_to_sync(txg_handle_t *th)
{
	tx_cpu_t *tc = th->th_cpu;
	int g = th->th_txg & TXG_MASK;

	mutex_enter(&tc->tc_lock);
	ASSERT(tc->tc_count[g] != 0);
	if (--tc->tc_count[g] == 0)
		cv_broadcast(&tc->tc_cv[g]);
	mutex_exit(&tc->tc_lock);

	th->th_cpu = NULL;	/* defensive */
}

static void
txg_quiesce(dsl_pool_t *dp, uint64_t txg)
{
	tx_state_t *tx = &dp->dp_tx;
	int g = txg & TXG_MASK;
	int c;

	/*
	 * Grab all tx_cpu locks so nobody else can get into this txg.
	 */
	for (c = 0; c < max_ncpus; c++)
		mutex_enter(&tx->tx_cpu[c].tc_lock);

	ASSERT(txg == tx->tx_open_txg);
	tx->tx_open_txg++;

	/*
	 * Now that we've incremented tx_open_txg, we can let threads
	 * enter the next transaction group.
	 */
	for (c = 0; c < max_ncpus; c++)
		mutex_exit(&tx->tx_cpu[c].tc_lock);

	/*
	 * Quiesce the transaction group by waiting for everyone to txg_exit().
	 */
	for (c = 0; c < max_ncpus; c++) {
		tx_cpu_t *tc = &tx->tx_cpu[c];
		mutex_enter(&tc->tc_lock);
		while (tc->tc_count[g] != 0)
			cv_wait(&tc->tc_cv[g], &tc->tc_lock);
		mutex_exit(&tc->tc_lock);
	}
}

static void
txg_sync_thread(dsl_pool_t *dp)
{
	tx_state_t *tx = &dp->dp_tx;
	callb_cpr_t cpr;
	uint64_t start, delta;

	txg_thread_enter(tx, &cpr);

	start = delta = 0;
	for (;;) {
		uint64_t timer, timeout = zfs_txg_timeout * hz;
		uint64_t txg;

		/*
		 * We sync when we're scrubbing, there's someone waiting
		 * on us, or the quiesce thread has handed off a txg to
		 * us, or we have reached our timeout.
		 */
		timer = (delta >= timeout ? 0 : timeout - delta);
		while ((dp->dp_scrub_func == SCRUB_FUNC_NONE ||
		    spa_shutting_down(dp->dp_spa)) &&
		    !tx->tx_exiting && timer > 0 &&
		    tx->tx_synced_txg >= tx->tx_sync_txg_waiting &&
		    tx->tx_quiesced_txg == 0) {
			dprintf("waiting; tx_synced=%llu waiting=%llu dp=%p\n",
			    tx->tx_synced_txg, tx->tx_sync_txg_waiting, dp);
			txg_thread_wait(tx, &cpr, &tx->tx_sync_more_cv, timer);
			delta = lbolt - start;
			timer = (delta > timeout ? 0 : timeout - delta);
		}

		/*
		 * Wait until the quiesce thread hands off a txg to us,
		 * prompting it to do so if necessary.
		 */
		while (!tx->tx_exiting && tx->tx_quiesced_txg == 0) {
			if (tx->tx_quiesce_txg_waiting < tx->tx_open_txg+1)
				tx->tx_quiesce_txg_waiting = tx->tx_open_txg+1;
			cv_broadcast(&tx->tx_quiesce_more_cv);
			txg_thread_wait(tx, &cpr, &tx->tx_quiesce_done_cv, 0);
		}

		if (tx->tx_exiting)
			txg_thread_exit(tx, &cpr, &tx->tx_sync_thread);

		rw_enter(&tx->tx_suspend, RW_WRITER);

		/*
		 * Consume the quiesced txg which has been handed off to
		 * us.  This may cause the quiescing thread to now be
		 * able to quiesce another txg, so we must signal it.
		 */
		txg = tx->tx_quiesced_txg;
		tx->tx_quiesced_txg = 0;
		tx->tx_syncing_txg = txg;
		cv_broadcast(&tx->tx_quiesce_more_cv);
		rw_exit(&tx->tx_suspend);

		dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
		    txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
		mutex_exit(&tx->tx_sync_lock);

		start = lbolt;
		spa_sync(dp->dp_spa, txg);
		delta = lbolt - start;

		mutex_enter(&tx->tx_sync_lock);
		rw_enter(&tx->tx_suspend, RW_WRITER);
		tx->tx_synced_txg = txg;
		tx->tx_syncing_txg = 0;
		rw_exit(&tx->tx_suspend);
		cv_broadcast(&tx->tx_sync_done_cv);
	}
}

static void
txg_quiesce_thread(dsl_pool_t *dp)
{
	tx_state_t *tx = &dp->dp_tx;
	callb_cpr_t cpr;

	txg_thread_enter(tx, &cpr);

	for (;;) {
		uint64_t txg;

		/*
		 * We quiesce when there's someone waiting on us.
		 * However, we can only have one txg in "quiescing" or
		 * "quiesced, waiting to sync" state.  So we wait until
		 * the "quiesced, waiting to sync" txg has been consumed
		 * by the sync thread.
		 */
		while (!tx->tx_exiting &&
		    (tx->tx_open_txg >= tx->tx_quiesce_txg_waiting ||
		    tx->tx_quiesced_txg != 0))
			txg_thread_wait(tx, &cpr, &tx->tx_quiesce_more_cv, 0);

		if (tx->tx_exiting)
			txg_thread_exit(tx, &cpr, &tx->tx_quiesce_thread);

		txg = tx->tx_open_txg;
		dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
		    txg, tx->tx_quiesce_txg_waiting,
		    tx->tx_sync_txg_waiting);
		mutex_exit(&tx->tx_sync_lock);
		txg_quiesce(dp, txg);
		mutex_enter(&tx->tx_sync_lock);

		/*
		 * Hand this txg off to the sync thread.
		 */
		dprintf("quiesce done, handing off txg %llu\n", txg);
		tx->tx_quiesced_txg = txg;
		cv_broadcast(&tx->tx_sync_more_cv);
		cv_broadcast(&tx->tx_quiesce_done_cv);
	}
}

/*
 * Delay this thread by 'ticks' if we are still in the open transaction
 * group and there is already a waiting txg quiesing or quiesced.  Abort
 * the delay if this txg stalls or enters the quiesing state.
 */
void
txg_delay(dsl_pool_t *dp, uint64_t txg, int ticks)
{
	tx_state_t *tx = &dp->dp_tx;
	int timeout = lbolt + ticks;

	/* don't delay if this txg could transition to quiesing immediately */
	if (tx->tx_open_txg > txg ||
	    tx->tx_syncing_txg == txg-1 || tx->tx_synced_txg == txg-1)
		return;

	mutex_enter(&tx->tx_sync_lock);
	if (tx->tx_open_txg > txg || tx->tx_synced_txg == txg-1) {
		mutex_exit(&tx->tx_sync_lock);
		return;
	}

	while (lbolt < timeout &&
	    tx->tx_syncing_txg < txg-1 && !txg_stalled(dp))
		(void) cv_timedwait(&tx->tx_quiesce_more_cv, &tx->tx_sync_lock,
		    timeout);

	mutex_exit(&tx->tx_sync_lock);
}

void
txg_wait_synced(dsl_pool_t *dp, uint64_t txg)
{
	tx_state_t *tx = &dp->dp_tx;

	mutex_enter(&tx->tx_sync_lock);
	ASSERT(tx->tx_threads == 2);
	if (txg == 0)
		txg = tx->tx_open_txg;
	if (tx->tx_sync_txg_waiting < txg)
		tx->tx_sync_txg_waiting = txg;
	dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
	    txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
	while (tx->tx_synced_txg < txg) {
		dprintf("broadcasting sync more "
		    "tx_synced=%llu waiting=%llu dp=%p\n",
		    tx->tx_synced_txg, tx->tx_sync_txg_waiting, dp);
		cv_broadcast(&tx->tx_sync_more_cv);
		cv_wait(&tx->tx_sync_done_cv, &tx->tx_sync_lock);
	}
	mutex_exit(&tx->tx_sync_lock);
}

void
txg_wait_open(dsl_pool_t *dp, uint64_t txg)
{
	tx_state_t *tx = &dp->dp_tx;

	mutex_enter(&tx->tx_sync_lock);
	ASSERT(tx->tx_threads == 2);
	if (txg == 0)
		txg = tx->tx_open_txg + 1;
	if (tx->tx_quiesce_txg_waiting < txg)
		tx->tx_quiesce_txg_waiting = txg;
	dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
	    txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
	while (tx->tx_open_txg < txg) {
		cv_broadcast(&tx->tx_quiesce_more_cv);
		cv_wait(&tx->tx_quiesce_done_cv, &tx->tx_sync_lock);
	}
	mutex_exit(&tx->tx_sync_lock);
}

boolean_t
txg_stalled(dsl_pool_t *dp)
{
	tx_state_t *tx = &dp->dp_tx;
	return (tx->tx_quiesce_txg_waiting > tx->tx_open_txg);
}

boolean_t
txg_sync_waiting(dsl_pool_t *dp)
{
	tx_state_t *tx = &dp->dp_tx;

	return (tx->tx_syncing_txg <= tx->tx_sync_txg_waiting ||
	    tx->tx_quiesced_txg != 0);
}

void
txg_suspend(dsl_pool_t *dp)
{
	tx_state_t *tx = &dp->dp_tx;
	/* XXX some code paths suspend when they are already suspended! */
	rw_enter(&tx->tx_suspend, RW_READER);
}

void
txg_resume(dsl_pool_t *dp)
{
	tx_state_t *tx = &dp->dp_tx;
	rw_exit(&tx->tx_suspend);
}

/*
 * Per-txg object lists.
 */
void
txg_list_create(txg_list_t *tl, size_t offset)
{
	int t;

	mutex_init(&tl->tl_lock, NULL, MUTEX_DEFAULT, NULL);

	tl->tl_offset = offset;

	for (t = 0; t < TXG_SIZE; t++)
		tl->tl_head[t] = NULL;
}

void
txg_list_destroy(txg_list_t *tl)
{
	int t;

	for (t = 0; t < TXG_SIZE; t++)
		ASSERT(txg_list_empty(tl, t));

	mutex_destroy(&tl->tl_lock);
}

int
txg_list_empty(txg_list_t *tl, uint64_t txg)
{
	return (tl->tl_head[txg & TXG_MASK] == NULL);
}

/*
 * Add an entry to the list.
 * Returns 0 if it's a new entry, 1 if it's already there.
 */
int
txg_list_add(txg_list_t *tl, void *p, uint64_t txg)
{
	int t = txg & TXG_MASK;
	txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
	int already_on_list;

	mutex_enter(&tl->tl_lock);
	already_on_list = tn->tn_member[t];
	if (!already_on_list) {
		tn->tn_member[t] = 1;
		tn->tn_next[t] = tl->tl_head[t];
		tl->tl_head[t] = tn;
	}
	mutex_exit(&tl->tl_lock);

	return (already_on_list);
}

/*
 * Remove the head of the list and return it.
 */
void *
txg_list_remove(txg_list_t *tl, uint64_t txg)
{
	int t = txg & TXG_MASK;
	txg_node_t *tn;
	void *p = NULL;

	mutex_enter(&tl->tl_lock);
	if ((tn = tl->tl_head[t]) != NULL) {
		p = (char *)tn - tl->tl_offset;
		tl->tl_head[t] = tn->tn_next[t];
		tn->tn_next[t] = NULL;
		tn->tn_member[t] = 0;
	}
	mutex_exit(&tl->tl_lock);

	return (p);
}

/*
 * Remove a specific item from the list and return it.
 */
void *
txg_list_remove_this(txg_list_t *tl, void *p, uint64_t txg)
{
	int t = txg & TXG_MASK;
	txg_node_t *tn, **tp;

	mutex_enter(&tl->tl_lock);

	for (tp = &tl->tl_head[t]; (tn = *tp) != NULL; tp = &tn->tn_next[t]) {
		if ((char *)tn - tl->tl_offset == p) {
			*tp = tn->tn_next[t];
			tn->tn_next[t] = NULL;
			tn->tn_member[t] = 0;
			mutex_exit(&tl->tl_lock);
			return (p);
		}
	}

	mutex_exit(&tl->tl_lock);

	return (NULL);
}

int
txg_list_member(txg_list_t *tl, void *p, uint64_t txg)
{
	int t = txg & TXG_MASK;
	txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);

	return (tn->tn_member[t]);
}

/*
 * Walk a txg list -- only safe if you know it's not changing.
 */
void *
txg_list_head(txg_list_t *tl, uint64_t txg)
{
	int t = txg & TXG_MASK;
	txg_node_t *tn = tl->tl_head[t];

	return (tn == NULL ? NULL : (char *)tn - tl->tl_offset);
}

void *
txg_list_next(txg_list_t *tl, void *p, uint64_t txg)
{
	int t = txg & TXG_MASK;
	txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);

	tn = tn->tn_next[t];

	return (tn == NULL ? NULL : (char *)tn - tl->tl_offset);
}
Commit	Line	Data
34dc7c2f BB	1	/*
	2	* CDDL HEADER START
	3	*
	4	* The contents of this file are subject to the terms of the
	5	* Common Development and Distribution License (the "License").
	6	* You may not use this file except in compliance with the License.
	7	*
	8	* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
	9	* or http://www.opensolaris.org/os/licensing.
	10	* See the License for the specific language governing permissions
	11	* and limitations under the License.
	12	*
	13	* When distributing Covered Code, include this CDDL HEADER in each
	14	* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
	15	* If applicable, add the following below this CDDL HEADER, with the
	16	* fields enclosed by brackets "[]" replaced with your own identifying
	17	* information: Portions Copyright [yyyy] [name of copyright owner]
	18	*
	19	* CDDL HEADER END
	20	*/
	21	/*
	22	* Copyright 2008 Sun Microsystems, Inc. All rights reserved.
	23	* Use is subject to license terms.
	24	*/
	25
34dc7c2f BB	26	#include <sys/zfs_context.h>
	27	#include <sys/txg_impl.h>
	28	#include <sys/dmu_impl.h>
	29	#include <sys/dsl_pool.h>
	30	#include <sys/callb.h>
	31
	32	/*
	33	* Pool-wide transaction groups.
	34	*/
	35
	36	static void txg_sync_thread(dsl_pool_t *dp);
	37	static void txg_quiesce_thread(dsl_pool_t *dp);
	38
	39	int zfs_txg_timeout = 30; /* max seconds worth of delta per txg */
34dc7c2f BB	40
	41	/*
	42	* Prepare the txg subsystem.
	43	*/
	44	void
	45	txg_init(dsl_pool_t *dp, uint64_t txg)
	46	{
	47	tx_state_t *tx = &dp->dp_tx;
	48	int c;
	49	bzero(tx, sizeof (tx_state_t));
	50
	51	tx->tx_cpu = kmem_zalloc(max_ncpus * sizeof (tx_cpu_t), KM_SLEEP);
	52
	53	for (c = 0; c < max_ncpus; c++) {
	54	int i;
	55
	56	mutex_init(&tx->tx_cpu[c].tc_lock, NULL, MUTEX_DEFAULT, NULL);
	57	for (i = 0; i < TXG_SIZE; i++) {
	58	cv_init(&tx->tx_cpu[c].tc_cv[i], NULL, CV_DEFAULT,
	59	NULL);
	60	}
	61	}
	62
	63	rw_init(&tx->tx_suspend, NULL, RW_DEFAULT, NULL);
	64	mutex_init(&tx->tx_sync_lock, NULL, MUTEX_DEFAULT, NULL);
	65
fb5f0bc8 BB	66	cv_init(&tx->tx_sync_more_cv, NULL, CV_DEFAULT, NULL);
	67	cv_init(&tx->tx_sync_done_cv, NULL, CV_DEFAULT, NULL);
	68	cv_init(&tx->tx_quiesce_more_cv, NULL, CV_DEFAULT, NULL);
	69	cv_init(&tx->tx_quiesce_done_cv, NULL, CV_DEFAULT, NULL);
	70	cv_init(&tx->tx_exit_cv, NULL, CV_DEFAULT, NULL);
	71
34dc7c2f BB	72	tx->tx_open_txg = txg;
	73	}
	74
	75	/*
	76	* Close down the txg subsystem.
	77	*/
	78	void
	79	txg_fini(dsl_pool_t *dp)
	80	{
	81	tx_state_t *tx = &dp->dp_tx;
	82	int c;
	83
	84	ASSERT(tx->tx_threads == 0);
	85
	86	rw_destroy(&tx->tx_suspend);
	87	mutex_destroy(&tx->tx_sync_lock);
	88
fb5f0bc8 BB	89	cv_destroy(&tx->tx_sync_more_cv);
	90	cv_destroy(&tx->tx_sync_done_cv);
	91	cv_destroy(&tx->tx_quiesce_more_cv);
	92	cv_destroy(&tx->tx_quiesce_done_cv);
	93	cv_destroy(&tx->tx_exit_cv);
	94
34dc7c2f BB	95	for (c = 0; c < max_ncpus; c++) {
	96	int i;
	97
	98	mutex_destroy(&tx->tx_cpu[c].tc_lock);
	99	for (i = 0; i < TXG_SIZE; i++)
	100	cv_destroy(&tx->tx_cpu[c].tc_cv[i]);
	101	}
	102
	103	kmem_free(tx->tx_cpu, max_ncpus * sizeof (tx_cpu_t));
	104
	105	bzero(tx, sizeof (tx_state_t));
	106	}
	107
	108	/*
	109	* Start syncing transaction groups.
	110	*/
	111	void
	112	txg_sync_start(dsl_pool_t *dp)
	113	{
	114	tx_state_t *tx = &dp->dp_tx;
	115
	116	mutex_enter(&tx->tx_sync_lock);
	117
	118	dprintf("pool %p\n", dp);
	119
	120	ASSERT(tx->tx_threads == 0);
	121
	122	tx->tx_threads = 2;
	123
	124	tx->tx_quiesce_thread = thread_create(NULL, 0, txg_quiesce_thread,
	125	dp, 0, &p0, TS_RUN, minclsyspri);
	126
b128c09f BB	127	/*
	128	* The sync thread can need a larger-than-default stack size on
	129	* 32-bit x86. This is due in part to nested pools and
	130	* scrub_visitbp() recursion.
	131	*/
	132	tx->tx_sync_thread = thread_create(NULL, 12<<10, txg_sync_thread,
34dc7c2f BB	133	dp, 0, &p0, TS_RUN, minclsyspri);
	134
	135	mutex_exit(&tx->tx_sync_lock);
	136	}
	137
	138	static void
	139	txg_thread_enter(tx_state_t tx, callb_cpr_t cpr)
	140	{
	141	CALLB_CPR_INIT(cpr, &tx->tx_sync_lock, callb_generic_cpr, FTAG);
	142	mutex_enter(&tx->tx_sync_lock);
	143	}
	144
	145	static void
	146	txg_thread_exit(tx_state_t tx, callb_cpr_t cpr, kthread_t **tpp)
	147	{
	148	ASSERT(*tpp != NULL);
	149	*tpp = NULL;
	150	tx->tx_threads--;
	151	cv_broadcast(&tx->tx_exit_cv);
	152	CALLB_CPR_EXIT(cpr); /* drops &tx->tx_sync_lock */
	153	thread_exit();
	154	}
	155
	156	static void
	157	txg_thread_wait(tx_state_t tx, callb_cpr_t cpr, kcondvar_t *cv, uint64_t time)
	158	{
	159	CALLB_CPR_SAFE_BEGIN(cpr);
	160
	161	if (time)
	162	(void) cv_timedwait(cv, &tx->tx_sync_lock, lbolt + time);
	163	else
	164	cv_wait(cv, &tx->tx_sync_lock);
	165
	166	CALLB_CPR_SAFE_END(cpr, &tx->tx_sync_lock);
	167	}
	168
	169	/*
	170	* Stop syncing transaction groups.
	171	*/
	172	void
	173	txg_sync_stop(dsl_pool_t *dp)
	174	{
	175	tx_state_t *tx = &dp->dp_tx;
	176
	177	dprintf("pool %p\n", dp);
	178	/*
	179	* Finish off any work in progress.
	180	*/
	181	ASSERT(tx->tx_threads == 2);
	182	txg_wait_synced(dp, 0);
	183
	184	/*
	185	* Wake all sync threads and wait for them to die.
	186	*/
	187	mutex_enter(&tx->tx_sync_lock);
	188
	189	ASSERT(tx->tx_threads == 2);
	190
	191	tx->tx_exiting = 1;
	192
	193	cv_broadcast(&tx->tx_quiesce_more_cv);
	194	cv_broadcast(&tx->tx_quiesce_done_cv);
	195	cv_broadcast(&tx->tx_sync_more_cv);
	196
197	while (tx->tx_threads != 0)
198	cv_wait(&tx->tx_exit_cv, &tx->tx_sync_lock);
199
200	tx->tx_exiting = 0;
201
202	mutex_exit(&tx->tx_sync_lock);
203	}
204
205	uint64_t
206	txg_hold_open(dsl_pool_t dp, txg_handle_t th)
207	{
208	tx_state_t *tx = &dp->dp_tx;
209	tx_cpu_t *tc = &tx->tx_cpu[CPU_SEQID];
210	uint64_t txg;
211
212	mutex_enter(&tc->tc_lock);
213
214	txg = tx->tx_open_txg;
215	tc->tc_count[txg & TXG_MASK]++;
216
217	th->th_cpu = tc;
218	th->th_txg = txg;
219
220	return (txg);
221	}
222
223	void
224	txg_rele_to_quiesce(txg_handle_t *th)
225	{
226	tx_cpu_t *tc = th->th_cpu;
227
228	mutex_exit(&tc->tc_lock);
229	}
230
231	void
232	txg_rele_to_sync(txg_handle_t *th)
233	{
234	tx_cpu_t *tc = th->th_cpu;
235	int g = th->th_txg & TXG_MASK;
236
237	mutex_enter(&tc->tc_lock);
238	ASSERT(tc->tc_count[g] != 0);
239	if (--tc->tc_count[g] == 0)
240	cv_broadcast(&tc->tc_cv[g]);
241	mutex_exit(&tc->tc_lock);
242
243	th->th_cpu = NULL; /* defensive */
244	}
245
246	static void
247	txg_quiesce(dsl_pool_t *dp, uint64_t txg)
248	{
249	tx_state_t *tx = &dp->dp_tx;
250	int g = txg & TXG_MASK;
251	int c;
252
253	/*
254	* Grab all tx_cpu locks so nobody else can get into this txg.
255	*/
256	for (c = 0; c < max_ncpus; c++)
257	mutex_enter(&tx->tx_cpu[c].tc_lock);
258
259	ASSERT(txg == tx->tx_open_txg);
260	tx->tx_open_txg++;
261
262	/*
263	* Now that we've incremented tx_open_txg, we can let threads
264	* enter the next transaction group.
265	*/
266	for (c = 0; c < max_ncpus; c++)
267	mutex_exit(&tx->tx_cpu[c].tc_lock);
268
269	/*
270	* Quiesce the transaction group by waiting for everyone to txg_exit().
271	*/
272	for (c = 0; c < max_ncpus; c++) {
273	tx_cpu_t *tc = &tx->tx_cpu[c];
274	mutex_enter(&tc->tc_lock);
275	while (tc->tc_count[g] != 0)
276	cv_wait(&tc->tc_cv[g], &tc->tc_lock);
277	mutex_exit(&tc->tc_lock);
278	}
279	}
280
281	static void
282	txg_sync_thread(dsl_pool_t *dp)
283	{
284	tx_state_t *tx = &dp->dp_tx;
285	callb_cpr_t cpr;
b128c09f	286	uint64_t start, delta;
34dc7c2f BB	287
	288	txg_thread_enter(tx, &cpr);
	289
	290	start = delta = 0;
34dc7c2f	291	for (;;) {
b128c09f BB	292	uint64_t timer, timeout = zfs_txg_timeout * hz;
b128c09f BB	293	uint64_t txg;
34dc7c2f BB	294
34dc7c2f BB	295	/*
b128c09f BB	296	* We sync when we're scrubbing, there's someone waiting
	297	* on us, or the quiesce thread has handed off a txg to
	298	* us, or we have reached our timeout.
34dc7c2f BB	299	*/
34dc7c2f BB	300	timer = (delta >= timeout ? 0 : timeout - delta);
b128c09f BB	301	while ((dp->dp_scrub_func == SCRUB_FUNC_NONE \|\|
	302	spa_shutting_down(dp->dp_spa)) &&
	303	!tx->tx_exiting && timer > 0 &&
34dc7c2f BB	304	tx->tx_synced_txg >= tx->tx_sync_txg_waiting &&
	305	tx->tx_quiesced_txg == 0) {
	306	dprintf("waiting; tx_synced=%llu waiting=%llu dp=%p\n",
	307	tx->tx_synced_txg, tx->tx_sync_txg_waiting, dp);
	308	txg_thread_wait(tx, &cpr, &tx->tx_sync_more_cv, timer);
	309	delta = lbolt - start;
	310	timer = (delta > timeout ? 0 : timeout - delta);
	311	}
	312
	313	/*
	314	* Wait until the quiesce thread hands off a txg to us,
	315	* prompting it to do so if necessary.
	316	*/
	317	while (!tx->tx_exiting && tx->tx_quiesced_txg == 0) {
	318	if (tx->tx_quiesce_txg_waiting < tx->tx_open_txg+1)
	319	tx->tx_quiesce_txg_waiting = tx->tx_open_txg+1;
	320	cv_broadcast(&tx->tx_quiesce_more_cv);
	321	txg_thread_wait(tx, &cpr, &tx->tx_quiesce_done_cv, 0);
	322	}
	323
	324	if (tx->tx_exiting)
	325	txg_thread_exit(tx, &cpr, &tx->tx_sync_thread);
	326
	327	rw_enter(&tx->tx_suspend, RW_WRITER);
	328
	329	/*
	330	* Consume the quiesced txg which has been handed off to
	331	* us. This may cause the quiescing thread to now be
	332	* able to quiesce another txg, so we must signal it.
	333	*/
	334	txg = tx->tx_quiesced_txg;
	335	tx->tx_quiesced_txg = 0;
	336	tx->tx_syncing_txg = txg;
	337	cv_broadcast(&tx->tx_quiesce_more_cv);
	338	rw_exit(&tx->tx_suspend);
	339
	340	dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
	341	txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
	342	mutex_exit(&tx->tx_sync_lock);
b128c09f	343
34dc7c2f BB	344	start = lbolt;
	345	spa_sync(dp->dp_spa, txg);
	346	delta = lbolt - start;
	347
34dc7c2f BB	348	mutex_enter(&tx->tx_sync_lock);
	349	rw_enter(&tx->tx_suspend, RW_WRITER);
	350	tx->tx_synced_txg = txg;
	351	tx->tx_syncing_txg = 0;
	352	rw_exit(&tx->tx_suspend);
	353	cv_broadcast(&tx->tx_sync_done_cv);
	354	}
	355	}
	356
	357	static void
	358	txg_quiesce_thread(dsl_pool_t *dp)
	359	{
	360	tx_state_t *tx = &dp->dp_tx;
	361	callb_cpr_t cpr;
	362
	363	txg_thread_enter(tx, &cpr);
	364
	365	for (;;) {
	366	uint64_t txg;
	367
	368	/*
	369	* We quiesce when there's someone waiting on us.
	370	* However, we can only have one txg in "quiescing" or
	371	* "quiesced, waiting to sync" state. So we wait until
	372	* the "quiesced, waiting to sync" txg has been consumed
	373	* by the sync thread.
	374	*/
	375	while (!tx->tx_exiting &&
	376	(tx->tx_open_txg >= tx->tx_quiesce_txg_waiting \|\|
	377	tx->tx_quiesced_txg != 0))
	378	txg_thread_wait(tx, &cpr, &tx->tx_quiesce_more_cv, 0);
	379
	380	if (tx->tx_exiting)
	381	txg_thread_exit(tx, &cpr, &tx->tx_quiesce_thread);
	382
	383	txg = tx->tx_open_txg;
	384	dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
	385	txg, tx->tx_quiesce_txg_waiting,
	386	tx->tx_sync_txg_waiting);
	387	mutex_exit(&tx->tx_sync_lock);
	388	txg_quiesce(dp, txg);
	389	mutex_enter(&tx->tx_sync_lock);
	390
	391	/*
	392	* Hand this txg off to the sync thread.
	393	*/
	394	dprintf("quiesce done, handing off txg %llu\n", txg);
	395	tx->tx_quiesced_txg = txg;
	396	cv_broadcast(&tx->tx_sync_more_cv);
	397	cv_broadcast(&tx->tx_quiesce_done_cv);
	398	}
	399	}
	400
	401	/*
	402	* Delay this thread by 'ticks' if we are still in the open transaction
	403	* group and there is already a waiting txg quiesing or quiesced. Abort
	404	* the delay if this txg stalls or enters the quiesing state.
	405	*/
	406	void
	407	txg_delay(dsl_pool_t *dp, uint64_t txg, int ticks)
	408	{
	409	tx_state_t *tx = &dp->dp_tx;
	410	int timeout = lbolt + ticks;
	411
412	/* don't delay if this txg could transition to quiesing immediately */
413	if (tx->tx_open_txg > txg \|\|
414	tx->tx_syncing_txg == txg-1 \|\| tx->tx_synced_txg == txg-1)
415	return;
416
417	mutex_enter(&tx->tx_sync_lock);
418	if (tx->tx_open_txg > txg \|\| tx->tx_synced_txg == txg-1) {
419	mutex_exit(&tx->tx_sync_lock);
420	return;
421	}
422
423	while (lbolt < timeout &&
424	tx->tx_syncing_txg < txg-1 && !txg_stalled(dp))
425	(void) cv_timedwait(&tx->tx_quiesce_more_cv, &tx->tx_sync_lock,
426	timeout);
427
428	mutex_exit(&tx->tx_sync_lock);
429	}
430
431	void
432	txg_wait_synced(dsl_pool_t *dp, uint64_t txg)
433	{
434	tx_state_t *tx = &dp->dp_tx;
435
436	mutex_enter(&tx->tx_sync_lock);
437	ASSERT(tx->tx_threads == 2);
438	if (txg == 0)
439	txg = tx->tx_open_txg;
440	if (tx->tx_sync_txg_waiting < txg)
441	tx->tx_sync_txg_waiting = txg;
442	dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
443	txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
444	while (tx->tx_synced_txg < txg) {
445	dprintf("broadcasting sync more "
446	"tx_synced=%llu waiting=%llu dp=%p\n",
447	tx->tx_synced_txg, tx->tx_sync_txg_waiting, dp);
448	cv_broadcast(&tx->tx_sync_more_cv);
449	cv_wait(&tx->tx_sync_done_cv, &tx->tx_sync_lock);
450	}
451	mutex_exit(&tx->tx_sync_lock);
452	}
453
454	void
455	txg_wait_open(dsl_pool_t *dp, uint64_t txg)
456	{
457	tx_state_t *tx = &dp->dp_tx;
458
459	mutex_enter(&tx->tx_sync_lock);
460	ASSERT(tx->tx_threads == 2);
461	if (txg == 0)
462	txg = tx->tx_open_txg + 1;
463	if (tx->tx_quiesce_txg_waiting < txg)
464	tx->tx_quiesce_txg_waiting = txg;
465	dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
466	txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
467	while (tx->tx_open_txg < txg) {
468	cv_broadcast(&tx->tx_quiesce_more_cv);
469	cv_wait(&tx->tx_quiesce_done_cv, &tx->tx_sync_lock);
470	}
471	mutex_exit(&tx->tx_sync_lock);
472	}
473
b128c09f	474	boolean_t
34dc7c2f BB	475	txg_stalled(dsl_pool_t *dp)
	476	{
	477	tx_state_t *tx = &dp->dp_tx;
	478	return (tx->tx_quiesce_txg_waiting > tx->tx_open_txg);
	479	}
	480
b128c09f BB	481	boolean_t
	482	txg_sync_waiting(dsl_pool_t *dp)
	483	{
	484	tx_state_t *tx = &dp->dp_tx;
	485
	486	return (tx->tx_syncing_txg <= tx->tx_sync_txg_waiting \|\|
	487	tx->tx_quiesced_txg != 0);
	488	}
	489
34dc7c2f BB	490	void
	491	txg_suspend(dsl_pool_t *dp)
	492	{
	493	tx_state_t *tx = &dp->dp_tx;
	494	/* XXX some code paths suspend when they are already suspended! */
	495	rw_enter(&tx->tx_suspend, RW_READER);
	496	}
	497
	498	void
	499	txg_resume(dsl_pool_t *dp)
	500	{
	501	tx_state_t *tx = &dp->dp_tx;
	502	rw_exit(&tx->tx_suspend);
	503	}
	504
	505	/*
	506	* Per-txg object lists.
	507	*/
	508	void
	509	txg_list_create(txg_list_t *tl, size_t offset)
	510	{
	511	int t;
	512
	513	mutex_init(&tl->tl_lock, NULL, MUTEX_DEFAULT, NULL);
	514
	515	tl->tl_offset = offset;
	516
	517	for (t = 0; t < TXG_SIZE; t++)
	518	tl->tl_head[t] = NULL;
	519	}
	520
	521	void
	522	txg_list_destroy(txg_list_t *tl)
	523	{
	524	int t;
	525
	526	for (t = 0; t < TXG_SIZE; t++)
	527	ASSERT(txg_list_empty(tl, t));
	528
	529	mutex_destroy(&tl->tl_lock);
	530	}
	531
	532	int
	533	txg_list_empty(txg_list_t *tl, uint64_t txg)
	534	{
	535	return (tl->tl_head[txg & TXG_MASK] == NULL);
	536	}
	537
	538	/*
	539	* Add an entry to the list.
	540	* Returns 0 if it's a new entry, 1 if it's already there.
	541	*/
	542	int
	543	txg_list_add(txg_list_t tl, void p, uint64_t txg)
	544	{
	545	int t = txg & TXG_MASK;
	546	txg_node_t tn = (txg_node_t )((char *)p + tl->tl_offset);
	547	int already_on_list;
	548
	549	mutex_enter(&tl->tl_lock);
	550	already_on_list = tn->tn_member[t];
	551	if (!already_on_list) {
	552	tn->tn_member[t] = 1;
	553	tn->tn_next[t] = tl->tl_head[t];
554	tl->tl_head[t] = tn;
555	}
556	mutex_exit(&tl->tl_lock);
557
558	return (already_on_list);
559	}
560
561	/*
562	* Remove the head of the list and return it.
563	*/
564	void *
565	txg_list_remove(txg_list_t *tl, uint64_t txg)
566	{
567	int t = txg & TXG_MASK;
568	txg_node_t *tn;
569	void *p = NULL;
570
571	mutex_enter(&tl->tl_lock);
572	if ((tn = tl->tl_head[t]) != NULL) {
573	p = (char *)tn - tl->tl_offset;
574	tl->tl_head[t] = tn->tn_next[t];
575	tn->tn_next[t] = NULL;
576	tn->tn_member[t] = 0;
577	}
578	mutex_exit(&tl->tl_lock);
579
580	return (p);
581	}
582
583	/*
584	* Remove a specific item from the list and return it.
585	*/
586	void *
587	txg_list_remove_this(txg_list_t tl, void p, uint64_t txg)
588	{
589	int t = txg & TXG_MASK;
590	txg_node_t tn, *tp;
591
592	mutex_enter(&tl->tl_lock);
593
594	for (tp = &tl->tl_head[t]; (tn = *tp) != NULL; tp = &tn->tn_next[t]) {
595	if ((char *)tn - tl->tl_offset == p) {
596	*tp = tn->tn_next[t];
597	tn->tn_next[t] = NULL;
598	tn->tn_member[t] = 0;
599	mutex_exit(&tl->tl_lock);
600	return (p);
601	}
602	}
603
604	mutex_exit(&tl->tl_lock);
605
606	return (NULL);
607	}
608
609	int
610	txg_list_member(txg_list_t tl, void p, uint64_t txg)
611	{
612	int t = txg & TXG_MASK;
613	txg_node_t tn = (txg_node_t )((char *)p + tl->tl_offset);
614
615	return (tn->tn_member[t]);
616	}
617
618	/*
619	* Walk a txg list -- only safe if you know it's not changing.
620	*/
621	void *
622	txg_list_head(txg_list_t *tl, uint64_t txg)
623	{
624	int t = txg & TXG_MASK;
625	txg_node_t *tn = tl->tl_head[t];
626
627	return (tn == NULL ? NULL : (char *)tn - tl->tl_offset);
628	}
629
630	void *
631	txg_list_next(txg_list_t tl, void p, uint64_t txg)
632	{
633	int t = txg & TXG_MASK;
634	txg_node_t tn = (txg_node_t )((char *)p + tl->tl_offset);
635
636	tn = tn->tn_next[t];
637
638	return (tn == NULL ? NULL : (char *)tn - tl->tl_offset);
639	}